The Occipitomastoid Suture as a Novel Landmark to Identify the Occipital Groove and Proximal Segment of the Occipital Artery Halima Tabani MD; Sirin Gandhi MD; Roberto Rodriguez Rubio MD; Michael T. Lawton MD; Arnau Benet M.D. University of California, San Francisco Introduction Results Conclusions The occipital artery (OA) is commonly used as a In 71.5% of the specimens the OA ran in a groove, The OMS is a key landmark for localizing the donor for posterior circulation bypass procedures. while it carved an impression in the rest of the proximal OA. The OMS can be followed inferiorly Localization of OA during harvesting is important to cases (28.5%). In none of the specimens the OA prevent inadvertent damage to the donor. The was found to run in a bony canal. In 68.6% of the from the asterion to the OA groove, thereby proximal portion of the OA is found in the occipital cases, the OMS was found to be medial to the OA localizing the proximal OA. Inadvertent damage to groove. The occipitomastoid suture (OMS) is located groove or impression while in 31.4%, it ran the proximal OA may be avoided by identifying the between the occipital bone and the mastoid portion centrally through the OA groove or impression OMS and dissecting medial to it, since in majority of the temporal bone. This study aimed to assess (Figure 1). The OMS was never found lateral to the of cases, the proximal OA will be located lateral to the relationship between the OMS and the occipital OA it groove, in order to facilitate localization of the proximal portion of OA while harvesting it for bypass Learning Objectives 1.To understand the relationship between the Figure 1 occipital groove and the occiptomastoid suture 2.To understand the potential use of occipitomastoid suture as a landmark to identify the proximal Methods segment of OA in the occipital groove Thirty-five dry skulls were assessed bilaterally (n=70) to study the bony landmarks that can be used to identify and locate the proximal segment of OA. The occipital groove (OG) was bilaterally References Dry skull images depicting the relationship between identified in each skull and its shape was classified 1. Alvernia JE, Fraser K, Lanzino G: The occipital digastric groove, occipital groove, and occipito-mastoid into canal, groove or impression. The asterion was artery: a microanatomical study. Neurosurgery suture (OMS). located and the origin of OMS was identified. The 58:ONS114-122; discussion ONS114-122, 2006 (A) The morphologic configuration where the OMS is OMS was then followed inferiorly to assess its 2. Ates O, Ahmed AS, Niemann D, Baskaya MK: The medial to the occipital groove is shown. The foramen for relationship with the course of the OA (medial, occipital artery for posterior circulation bypass: the mastoid emissary vein is also visible (B) The lateral or central) microsurgical anatomy. Neurosurg Focus 24:E9, morphologic configuration where the OMS is running 2008 through the occipital groove is depicted. The asterion is shown; the OMS can be followed from the asterion inferiorly to locate the occipital groove, and thus, the OA.